1. Field of the Invention
The present invention relates to a technology applicable for an electronic equipment mounting electronic parts (particularly, a mobile product required high impact strength), a CSP package required resistance of thermal shock, a MCM (multi-chip module) as a semiconductor module, a semiconductor device die-bonded Si chip or the like, connection of a large area power module, and so forth.
2. Description of the Related Art
Currently, in viewpoint of environmental protection, use of Pb free soldering is promoted. It is a worldwide trend irrespective of kind of electronic equipments that solder is transiting from conventional Snxe2x80x94Pb eutectic type solder to high temperature type solder of Snxe2x80x94Agxe2x80x94Cu type, such as Sn-(2.0xcx9c4.0)Ag-(0.5xcx9c1.5)Cu, which can expect high reliability of joint. In comparison with the conventional full universal type Snxe2x80x94Pb eutectic type solder, Snxe2x80x94Agxe2x80x94Cu type solder has to pay attention for possibility of degradation of reliability of connection in some intended use of product or usage, due to essential difference of metals, particularly due to difference of mechanical strength characteristics.
In general, in comparison with Snxe2x80x94Pb eutectic solder, Snxe2x80x94Agxe2x80x94Cu type solder per se has high strength, high rigidity and high joint interface strength for current melallization. When the parts, printed circuit board and so forth have high strength, Snxe2x80x94Agxe2x80x94Cu type solder may achieve reliability comparable or higher than mounting products of the conventional Snxe2x80x94Pb solder.
However, in contrast to this, when parts, printed circuit board and so forth is low in strength, since solder per se is not broken, stress concentration is caused at joint interface to possibly damage the parts or the like. The important reason is that Snxe2x80x94Agxe2x80x94Cu type solder has a property of high strength as mechanical property. For example, in the electronic equipment mounting electronic parts (particularly, moving type mobile product, such as cellular telephone), while Snxe2x80x94Agxe2x80x94Cu type solder has high reliability, such as joint strength or the like, it has been pointed out that it has low strength against impact, such as upon falling down, thermal shock and so forth, from experimental facts.
It is an object of the present invention to improve falling down shock resistance or impact resistance in an electronic equipment.
Another object of the present invention is to improve reliability of a solder joint in a semiconductor device die-bonded Si chip or the like to which thermal shock causing large deformation may act, bump mounting of BGA, CSP, WPP, flip-chip and so forth, a power module acting large stress and so forth.
In order to accomplish the above-mentioned object, according to the first aspect of the present invention, an electronic equipment has a circuit board and an electronic parts to be electrically connected to an electrode of the circuit board, wherein, as described in Claims of the present application, the electrode of the circuit board and an electrode of the electronic part being connected by soldering using a lead free solder including:
Cu: 0xcx9c2.0 mass %;
In: 0.1xcx9c7.0 mass %; and
Sn: remaining amount.
Preferably, the lead free solder may be including:
Cu: 0.1xcx9c1.5 mass %;
In: 0.5xcx9c2.0 mass %; and
Sn: remaining amount.
Also, the lead free solder may be consisted of:
Cu: 0.1xcx9c1.5 mass %;
In: 0.5xcx9c7.0 mass %;
Ag: 0xcx9c1.0 mass %; and
Sn: remaining amount.
In the further alternative, lead free solder may be including:
Cu: 0.1xcx9c1.5 mass %;
In: 0.5xcx9c7.0 mass %;
Ag: 0xcx9c1.0 mass % and
Sn: remaining amount.
The electrode of the electronic part may be a solder bump formed with lead free solder.
The electrode of the electronic part may be solder connected by forming a plating layer of Sn-(1xcx9c10) mass % Bi.
The solder connection may be established by forming a plating layer of Sn-(0.2xcx9c2) mass % Cu on the electrode of the electronic part.
According to the second aspect of the present invention, a semiconductor device comprises a semiconductor element and a bump to be electrically connected to the semiconductor element, the solder bump being lead free solder including:
Cu: 0xcx9c2.0 mass %;
In: 0.1xcx9c7.0 mass %; and
Sn: in remaining amount.
According to the third aspect of the invention, a semiconductor module having a circuit board and an electronic parts to be electrically connected to an electrode of the circuit board, wherein the circuit board and an external connection terminal to be externally connecting portion to be connected electrically being connected by soldering using a lead free solder including:
Cu: 0xcx9c2.0 mass %;
In: 0.1xcx9c7.0 mass %; and
Sn: remaining amount.
More particularly, by employing a material easy to deform and superior to elongate than Snxe2x80x94Agxe2x80x94Cu type solder when impulsive large force act on the solder, stress load in the joint interface of the parts can be eliminated without degrading reliability in heat cycle of the joint to improve falling down resistance and impact resistance to improve thermal shock absorbing function for large deformation. Namely, as Pb free solder of Sn base used in the joint portion, a material having small stress and material easy to deform is prepared by solving In which is softer than Sn in the matrix of Sn or Snxe2x80x94Cu to improve falling down resistance and impact resistance by absorbing impact to be exerted on the joint interface as falling down.
By this, impact energy upon falling down is absorbed by plastic deformation of the solder per se to reduce stress to be exerted on the joint interface. Therefore, large impact force will not act on the joint interface to improve impact resistance.
On the other hand, even in solder bump connection of the semiconductor device die-bonded the Si-chip or the like, mounting of BGA, CSP, WPP (Wafer Process Package), flip-chip and connection of large area power module to which large stress act, upon soldering causing large deformation and upon thermal shock acceleration test or the like, breakage due to stress concentration at the interface is prevented and reliability of connection can be achieved by employing a material having low strength and easy to deform.